Branch vessel graft design and deployment method

ABSTRACT

A branch graft stent system includes a tubular primary graft having a branch graft opening which when deployed is located in alignment with a side branch vessel emanating from the primary vessel in which a branch graft is deployed. A connector (flange) member forms a perimeter of the branch graft opening and is constructed so that the connector member is substantially flush with the wall of the tubular primary graft. The tubular branch graft has a first expandable ring and a second expandable ring spaced apart from each other as part of a connection section located at a proximal end of the tubular branch graft. The first expandable ring, the second expandable ring, and graft or other material spaced between the first expandable ring and the second expandable ring when engaged with the perimeter of the branch graft opening of the primary graft, the assembly forms a flexible sealed connection between the primary graft and branch graft lumens to continue to exclude the aneurysm while providing a conduit for blood flow to the branch vessel. A distal end of the branch graft can be anchored by a balloon expandable or a self-expanding stent to the wall of the branch vessel beyond the aneurysm.

FIELD OF THE INVENTION

This invention relates generally to endoluminal medical devices andprocedures, and more particularly to branch vessel grafts secondarilyattached to a main vessel stent graft using a system of rings coupled tothe branch graft for a sealed branch vessel graft connection to a mainstent graft.

BACKGROUND OF THE INVENTION

Prostheses for implantation in blood vessels or other similar organs ofthe living body are, in general, well known in the medical art. Forexample, prosthetic vascular grafts formed of biocompatible materials(e.g., Dacron or expanded, porous polytetrafluoroethylene (PTFE) tubing)have been employed to replace or bypass damaged or occluded naturalblood vessels. A graft material supported by framework is known as astent graft. In general, the use of stent grafts for treatment orisolation of vascular aneurysms and vessel walls which have been thinnedor thickened by disease (endoluminal repair or exclusion) are wellknown. Many stent grafts, are “self-expanding”, i.e., inserted into thevascular system in a compressed or contracted state, and permitted toexpand upon removal of a restraint. Self-expanding stent graftstypically employ a wire or tube configured (e.g. bent or cut) to providean outward radial force and employ a suitable elastic material such asstainless steel or Nitinol (nickel-titanium). Nitinol may additionallyemploy shape memory properties. The self-expanding stent graft istypically configured in a tubular shape of a slightly greater diameterthan the diameter of the blood vessel in which the stent graft isintended to be used. In general, rather than performing an open surgicalprocedure which is traumatic and invasive to implant a bypass graft,stents and stent grafts are preferably deployed through a less invasiveintraluminal delivery, i.e., cutting through the skin to access a lumenor vasculature or percutaneously via successive dilatation, at aconvenient (and less traumatic) entry point, and routing the stent graftthrough the vascular lumen to the site where the prosthesis is to bedeployed.

Intraluminal deployment is typically effected using a delivery catheterwith a coaxial inner (plunger member) and an outer (sheath) tubesarranged for relative axial movement. The stent (or stent graft) iscompressed and disposed within the distal end of an outer catheter tubein front of a stent stop fixed to the inner member. The catheter is thenmaneuvered, typically routed though a lumen (e.g., vessel), until theend of the catheter (and the stent graft) is positioned at the intendedtreatment site. The stent stop on the inner member is then heldstationary while the sheath of the delivery catheter is withdrawn. Theinner member prevents the stent graft from being withdrawn with thesheath. As the sheath is withdrawn, the stent graft is released from theconfines of the sheath and radially expands so that at least a portionof it is in substantially conforming surface contact with a portion ofthe surrounding interior of the lumen e.g., blood vessel wall oranatomical conduit. As a convention used to describe the ends of devicesimplanted in the arterial system the proximal end of the stent graft isthe end closest to the heart as taken along the path of blood flow fromthe heart, whereas the distal end is the end furthest away from theheart once deployed. An example of stent graft positioning anddeployment is shown in FIG. 1, which is a figure taken from U.S. Pat.No. 5,591,195 to Taheri et al.

FIG. 1 shows an aneurysm 30 in a vascular artery 32 (such as an aorta).A stent graft 34 spanning the aneurysmal sac 36 is show as just havingbeen deployed from a delivery system 38. The stent graft 34 isconstructed of a tubular graft (textile or cloth) material 40 which ateach tubular end is radially expanded by zig zag type (Z-type) tubularstents 42, 44. A connecting bar 46 (shown in dashed lines) connects thetwo end stents 42, 44. The stent graft 34 deployed at the location ofthe aneurysm 30 creates a separate isolated flow path for blood throughthe lumen of the stent graft 34 such that the aneurysmal sac 36 of theaneurysm 30 is excluded and is no longer subject to the normal maximumblood pressure experienced in the vascular arterial system at thelocation of the aneurysm 30. Depending on the construction of the graftmaterial 40 it may either seal immediately or provide a very slightpermeable leakage (blush) which through the biological activity in theblood stream will cause the graft material 42 to be tightly sealed overtime.

Stent grafts can also be used in patients diagnosed with aneurysms closeto or crossing branch openings to renal arteries or other brancharteries (e.g., celiac, suprarenal, interior mesenteric). Stent graftdesigns with side openings are designed for use in regions of the aortafrom which side branches feed blood to organs like the kidney, spleen,liver, and stomach. FIGS. 2 and 3 show examples from U.S. Pat. No.6,030,414 to Taheri, as described therein. Such endovascular grafts havebeen designed for use where the proximal end of the graft is securelyanchored in place, and fenestrations are configured and deployed toavoid blocking or restricting blood flow into the renal arteries. Theendovascular graft must be designed, implanted, and maintain position ina manner which does not impair the flow of blood into the brancharteries.

Stent grafts 50, 60 with side openings or fenestrations 52, 54, 62, 64are shown in FIGS. 2 and 3. Such fenestrations 52, 54, 62, 64 do notform discrete conduit(s) through which blood is channeled into eachbranch artery 51, 53, 61, 63, 67, 69. As a result, the edges of thegraft surrounding the fenestrations 52, 54, 62, 64 could be prone to: i)the leakage of blood into the space between the outer surface 56, 66 ofthe aortic graft(stent graft 50,60) and the surrounding aortic wall 55,65; or ii) post-implantation migration or movement of the stent graft50, 60 causing misalignment of the fenestration(s) 52, 54, 62, 64 andthe branch artery(ies) 51, 53, 61, 63, 67, 69—with resultant impairmentof flow into the branch artery(ies).

FIG. 4 shows an alternate prior art configuration for a stent graft 70having integrally constructed tubular branch members 71, 72, 73, 74,where the branch tubular members are placed into position using a seriesof guidewires 76, 77, 78, 79, where the top (proximal) end 80 fixed by aseparately delivered stent (not shown) above the aneurysmal part of theaorta. A full explanation of the mechanism for delivery and finalfixation of the stent graft with integral branches (as shown in FIG. 4)can be had by reference to U.S. Pat. No. 6,099,548 to Taheri thedisclosure of which is incorporated herein by reference.

FIGS. 5 and 6 show an alternate arrangement for construction of a branchvessel connection. FIGS. 5 and 6 are examples taken from U.S. Pat. No.6,059,824 to Taheri, incorporated herein by reference. In FIG. 5 themain stent body 90 once properly positioned in the main artery (notshown) has an opening wide annular land portion collar 93 aligned withside branching collateral arteries (not shown). The wide annular landportion collar 93 includes a series of inlets (or indentations) 94 a, 94b. A collateral cylindrical stent body 92 is mated to the main stentbody 90 through an annular land portion flange located at the proximalend of the collateral cylindrical body 92. The annular land portioncollar 95 includes several detents 96 a, 96 b which are sized and spacedabout the annular extent of the collateral collar 95 to position, holdand lock the collateral stent cylindrical body 92 mated to the mainstent body 90. The detents, e.g. 96 a, 96 b, are received in the inletse.g. 94 a, 94 b, of the main stent collar 93. An engagement balloon (notshown) located in the aorta is used to provide the force needed to lockthe detents, e.g., 96 a, 96 b, and the inlets e.g., 94 a, 94 b,together.

FIGS. 7 and 8 show another prior art arrangement of a branch vesselconnection to a stent graft. These Figures are similar to those in U.S.Pat. No. 5,984,955 to Wisselink, incorporated herein by reference.Referring now to FIGS. 7 and 8 together, a primary graft 100 includes aring member 104 surrounding a side branch orifice 106 having afrustoconical member 102 extending from the graft 100. A side branchorifice 106 is aligned with the location of a branch artery (as seen inFIG. 8) and then a branch graft 110 is brought in through the main graftand snapped into position as the small ring member 114 and large ringmember 116 at the ends of the tapered proximal portion 112 of the branchgraft 110 are pushed into interfering engagement with the frustoconicalmember 102.

These examples of prior art devices to facilitate flow from ananeurysmal portion of the aorta into branch vessels show the complexityand space/volume requirements needed in the delivery system to deliverand accurately align such prior art systems. The use of fenestrations oropenings in a tubular graft requires that a perimeter opening be sealedagainst the vascular wall to prevent the blood from passing through thetubular graft from continuing to pressurize and enlarge the surroundinganeurysmal sac. Such a main graft body can be provided with a flange orother fitting which is hard to compress to insert into a deliverycatheter for deployment. And once the main stent graft body is inposition then branch members need to be positioned with great care toprovide a blood tight seal between the main graft body and the branchgraft.

Thus, a need exists for a method and deployment system that simplifiesalignment and reduces deployment forces needed to make a fluid tightconnection between a main stent graft and a branch graft connected to asidewall thereof. Ideally, such a branch graft is a part of a graftsystem that can treat aortic aneurysms at a location close to or at thelocation of a smaller vessel branching from the main vessel using abranch that makes a fluid tight connection to a port of the main graft.

Progress in this field looks to the development of new endovasculargrafting systems and methods which a) may be useable for endovasculargrafting in regions of a blood vessel (e.g., aorta) from which branchblood vessels (e.g., carotid, innominate, subclavian, intercostal,superior mesenteric, celiac, renal or iliac arteries) extend, and/or b)may enable more aortic aneurysm patients to be considered as candidatesfor endovascular repair, and/or c) may otherwise advance the state ofthe art of endovascular grafting to improve patient outcomes or lessencomplications.

SUMMARY OF THE INVENTION

A branch graft design according to the present invention provides animprovement in locating and connecting a stent graft to a branch vesselat the location of an aneurysm in the main vessel. A branch graft designincludes a tubular branch graft having a proximal end and a distal endand a lumen extending along the tubular branch graft axis longitudinallytherethrough. A first self-expanding support ring is coupled to a firstannular ring receiving section encircling the tubular branch graft atits proximal end. A second self-expanding support ring is coupled to asecond annular ring receiving section circumferentially encircling thetubular branch graft at its proximal end. The second annular ringreceiving section is disposed proximally parallel to and a ringreceiving section separation length along the branch graft axis from thefirst annular ring receiving section such that the second annularreceiving section is located closer to the distal end of the graft thanthe first annular ring receiving section. A tubular main graftconstructed of a main graft material has a side opening having aperimeter with a substantially flush reinforcing ring or flange. Thering receiving section separation portion of the branch graft materialengages the perimeter of the side opening to form a seal between themain graft and the branch graft when the first self expanding supportring which is coupled to the first annular ring receiving sectioncircumferentially encircling the branch graft at the proximal end isdisposed inside the side opening of the main graft and the second selfexpanding support ring which is coupled to the second annular ringreceiving section circumferentially encircling the branch graft at theproximal end is disposed outside the side opening of the branch graft.The support rings may be made of nitinol and configured in a multiplewinding hoop or a stent configuration and the support rings can be sewnto the inside or outside of tubular branch graft. The ring receivingseparation portion of the branch graft may be made from the samematerial as the tubular branch graft or of a semi-rigid (still pliable)material different from the material forming the tubular branch graft.

An embodiment according to the invention further includes a method fordeployment of a main stent graft and branch vessel graft comprising thesteps of at least partially deploying the main stent graft and aligninga substantially flush branch vessel port of the main stent graft with abranch vessel: deploying the branch vessel graft into the substantiallyflush branch vessel port wherein that the branch vessel graft is engagedwith the substantially flush branch vessel port of the main stent graftby exposing a first ring integral to the branch vessel graft to a firstside of the branch vessel port and subsequentially exposing a secondring integral to the branch vessel graft on an opposing side of thebranch vessel port.

The embodiment according to the invention can be further described toinclude a branch graft delivery system comprising a branch graftdisposed on a delivery catheter having a sheath surrounding a sealportion of the branch graft. The seal portion of the branch graftincludes a first annular self expanding ring section and a secondannular self expanding ring section. The ring sections arecircumferentially coupled to the graft at first and second locations,respectively, wherein the first and second locations are spaced fromeach by a cylindrical channel seal forming section. An inner member ofthe delivery catheter includes a first stop and a second stop each ofwhich extend laterally outward from the inner member to a diameterslightly less than the inside diameter of the delivery sheath. Annularspace between the inside diameter of the sheath and the outside diameterof the inner member provides clearance for the thickness of the graftmaterial to fit through and be carried in the annular space, whilepreventing the first and second annular self expanding support ringsections which are thicker because they contain or are attached to thesupport ring member from passing through the annular space. When thesheath is positioned to surround a first stop the first annular selfexpanding ring section is prevented from moving towards the secondannular self expanding ring section and when the sheath is positioned tosurround the second stop a second annular self expanding ring section isprevented from moving towards the first expanding ring section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a tubular stent graft ofthe prior art disposed across an aneurysm in an arterial vessel;

FIG. 2 is a schematic cross sectional view of a prior art stent grafthaving fenestrations which match side branch openings in a main arterialpassage having branch vessels extending from the main vessel;

FIG. 3 is a schematic cross sectional view of a stent graft deployedacross an aneurysm in an aorta, where the stent graft has fenestrationspositioned at locations so that branch vessels are fed through thefenestrations;

FIG. 4 is a schematic cross section showing a position of a stent graftwith several integral side branch graft passages in the process of beingpositioned to exclude blood flow to the aortic aneurysm while providingan artificial lumen to feed the branch vessels that originate in thearea of the aortic aneurysm;

FIGS. 5 and 6 show a pre assembly and post assembly, respectively,pictorial diagram of a main stent body to which a cylindrical collateralstent body is attached in situ;

FIGS. 7A, 7B and 8 show close up and schematic cross sectional diagramsof a branch graft connection to a primary stent graft providingbranching connections in an aorta where an aneurysmal sac has created awidening of the aorta at a location of branch vessels;

FIG. 9 is a schematic cross sectional view of a balloon expandablebranch graft configuration on its delivery system;

FIGS. 10 and 10A are a schematic cross sectional diagram and a close upview of a tip of a self expanding branch graft configuration on itsdelivery system;

FIGS. 11 and 11A are schematic cross sectional diagrams of a set of hoopor ring like self expanding support rings in a compressed configuration;

FIG. 12 is a schematic cross sectional of the support rings of the FIG.11 in an expanded (post deployed) configuration;

FIGS. 13A and 13B are side perspective diagrams showing a ring type selfexpanding support ring in a compressed (13A) and an expanded (13B)configuration as pictured in FIGS. 11 and 12, respectively;

FIG. 14 is schematic cross section showing an alternate configuration ofself expanding support rings where the support rings are configured froma stent of a zig zag configuration, the compressed state of the rings isshown;

FIGS. 15A, 15B, 15C, 15D, 15E, 15F, and 15G are schematic crosssectional diagrams showing the progressive steps of deployment of abranch graft assembly;

FIGS. 16A, 16B, 16C, 16D, 16L, 16F, and 16G are schematic crosssectional views of the steps in delivery and deployment of a branchgraft into a side branch vessel from an aneurysmal sac where a tubularmain graft has already been placed. The steps of deployment as picturedin FIGS. 16A-16G provide in situ view of the deployment of the branchgraft similar to, though not directly correlating to, the steps ofbranch deployment pictured in FIGS. 15A-15G described above.

FIG. 17 is a side plan view of a main tubular graft having a side branchopening (fenestration) therein;

FIG. 18 is a schematic cross sectional view showing one configuration ofa side branch graft connected with a tubular main graft;

FIG. 19 is a schematic cross sectional view showing anotherconfiguration of a tubular branch graft connected to a tubular maingraft; and

FIG. 20 is a schematic cross sectional view showing anotherconfiguration of a tubular branch graft connected to tubular main graft.

DETAILED DESCRIPTION

FIG. 9 shows a balloon expandable branch graft stent system 120 inaccordance with the invention. A catheter having a catheter inner member(inner tube) 122 extends from a proximal end 124 to a distal end 126 ofthe catheter. A balloon 128 is located at the distal end 126 of thecatheter and bonded to the catheter inner member 122 in a balloon tocatheter member distal bond region 132. The proximal end of the balloon128 is bonded at a balloon to outer member proximal bond region 130 toan outer member 144 that provides a coaxial annular lumen between itsinner surface and the outer surface of the catheter inner member 122.The balloon expandable stent 134 compressed around the balloon 128 ispositioned between a stent location proximal marker band 140 and a stentlocation distal marker band 142 both mounted on the catheter innermember 122. A tubular graft material 138 is sewn or bonded to theoutside of the stent in a stent to graft material bonding section 136.Tubular graft material 138 extends proximally from the stent 134 to adistal graft ring (hoop-stent) receiving section (pocket) 146 where aself expanding hoop or stent is disposed in a circumferential graftpocket containing a distal coiled nitinol hoop 156. An outer sheath 160prevents the distal coiled nitinol hoop 156 from expanding in a radialdirection while the axial limits of the distal graft ring receivingpocket 146 limits the axial movement (expansion) of the distal coilednitinol hoop 156. Similarly the graft 138 at its proximal end contains aproximal graft ring (hoop-stent) receiving section (pocket) 148 suchthat the axial length of the tubular graft material 138 extends from theproximal end of the proximal graft ring pocket 148 to the distal end ofthe stent 134 where it is attached (sewn or bonded) to a graft material136 in the stent to graft material bonding section 136. A proximalcoiled nitinol hoop 158 is contained within the proximal graft ring hoopreceiving section pocket 148. To maintain the position of the proximalgraft pocket 148 with respect to the distal graft pocket 146 and to thedistal end of the stent 134 a proximal ring (hoop) stop 152 and a distalring (hoop) stop 150 are fixed to the outer member (tube) 144 at adistance between ring (hoop) stops 154 spanned by a graft materialidentified as a ring receiving pockets separation section (sealingsection) 153. The distance between ring hoops stops 154 is dependentupon the main graft wall thickness, the branch vessel diameter, and themain graft wall opening diameter such that the specific dimensiondescribed for the distance between hoop ring stops 154 can lengthen orshorten depending on the interaction of the main graft wall thicknessthe branch vessel diameter and the main graft wall opening and diameteras appropriate for a particular application and branch graft diametersize. The sealing section 153 may be made of graft material or of a morerigid but still pliable material with good surface contact sealingcharacteristics.

FIG. 10 is a cross sectional schematic view of a self expanding branchgraft stent system 170. In this system a center member 172 extends toand is fixed to a catheter tip 174. A stent cup-disc plunger 176 (FIG.10A) is attached to the center member 172 such that a self expandingstent 178 to which a graft material 180 is attached is disposed betweenthe stent cup plunger 176 and the catheter tip 174. A full length sheath182 covers the full length of the center member 172 and seats in aperimeter groove on the catheter tip 174. Similar to the configurationdescribed for the balloon expandable system above, graft material 180contains a series of pockets to contain the distal expandable ring(hoop-stent) 184 and a similar ring pocket to contain the proximalexpandable ring (hoop-stent) 186. A distal ring (hoop-stent) stop 188and proximal ring (hoop-stent) stop 190 are fixed to the center member172 to maintain the pre deployment distance between the distalexpandable ring (hoop-stent) 184 and the proximal expandable ring(hoop-stent) 186.

FIG. 11 is a close up of a compressed configuration of expandable hooptype ring contained in a branch graft stent system. An outer sheath 194contains in a compressed configuration a graft material 196 which issewn or otherwise bonded to pocket material 202 and pocket material 204,respectively. A distal ring hoop pocket seam of the distal pocket shownas a dashed line 206 is the distal limit of the distal pocket containinga compressed coiled nitinol hoop 198 while a proximal ring hoop pocketseam shown as dashed line 208 of the distal pocket connects the distalpocket material 202 to the graft material 196 to act as a closed pouchto contain the compressed coiled nitinol hoop 198. Similarly acompressed proximal coiled nitinol hoop 200 is contained within a hooppocket (pouch) formed by proximal pocket material 204 which is bonded orsewn to the graft material 196 at coaxial circumferentially ring hooppocket seams, i.e., distal seam of the proximal pocket 210, and proximalseam of the proximal pocket 212. A ring receiving pocket separation(seal) section 214 separates the distal seam of the proximal pocket 210from the proximal seam of the distal pocket 208.

FIG. 11A is a close up of an alternate compressed configuration ofexpandable hoop type ring contained in a branch graft stent system ofthat shown in FIG. 11. An outer sheath 194′ contains in a compressedconfiguration graft material 196′ which is sewn or otherwise bonded topocket of pre enlarged material 2O3 forming a pocket for receiving andsetting the maximum diameter of expansion of a compressed coiled nitinolhoop 198′. A distal ring hoop pocket seam of the distal pocket shown asa dashed line 206′ in the distal limit of the distal pocket containing acompressed coiled nitinol hoop 198′ while a proximal ring hoop pocketseam shown as dashed line 208′ of the distal pocket connects the distalpocket material 202 to the graft material 196′ to act as a closed pouchto contain the compressed coiled nitinol hoop 198′. In this instance thegraft material 196′ which extends between the distal and proximal ringhoop pocket seams 206′ and 208′ has a bulge (disk creating) diameterwhich results in an annular fold of graft material that is folded overwhen the adjacent graft material (as shown in FIG. 11A) or tucked insideand not shown as seen or not seen in FIG. 11 such that stretching of thegraft material by the expanding ring (e.g., 198′) is not needed and doesnot take place. The angled (or tipped over) orientation of thecompressed coiled nitinol hoop 198′ shown in FIG. 11A, shows theposition of the end of the hoop in the end of the pocket 203, as mightbe experienced if a fully expanded hoop in a graft material pocket werecompressed to fit into a delivery sheath (e.g., 194′).

FIG. 12 shows configuration of the coiled nitinol hoops 198, 200 in anexpanded configuration. The sheath 194 shown in FIG. 11 having beenretracted, the distal nitinol hoop 198 has expanded from its compressedconfiguration as isolated in FIG. 13A shown as 198(c) to an expandedconfiguration as shown in FIG. 13B identified by 198(e). The proximalcoiled nitinol hoop 200 is similarly expanded so that the two expandedhoops contained within the hoop pocket spaces act as expanding discsalong the length of the graft material and create an expanding orsealing area at the ring receiving pocket separation section 214 (whichmay be very short length and have a diameter as large as if not largerthan, the main graft opening to which it is intended to seal).

FIG. 14 shows a self expanding configuration of a self expanding ringstent configuration. An outer sheath 217 contains in a compressedconfiguration a graft material 218 inside of which, or on the outside ofwhich, is attached or sewn in place a set of distal (220) and proximal(222) Z-type self expanding stents. The stents can be sewn to the insideor outside of the graft material or a pocket of material or pocket(pouch) space 224, 226 can be provided in which the self expandingstents 220, 222 can expand. The pockets 224, 226 have axial limits alongring stent pocket seams 228, 230, 232, 234. The graft material 218includes a ring receiving pocket separation (seal) section 236 betweenthe two central pockets seam 230, 232.

One sequence for deployment of a branch graft to be sealed to an openingin a main graft will now discussed by reference to FIGS. 15A-G and16A-G. Irrespective of whether a balloon expandable stent or a selfexpanding stent is used to anchor the distal end of the graft materialin the branch vessel, such a stent can be used solely to anchor thegraft or be used multifunctionally to anchor the graft and treat andprovide a lesion opening function when there is an occlusion ornarrowing in the branch vessel into which the branch graft system isbeing placed.

As can be seen in FIG. 16A a main vessel endovascular device 264 hasbeen placed across an aneurysm. The endovascular device 264 includes aside branch opening 266 through which a guidewire 260 is threaded intothe lumen contained by the branch vessel wall 262. The balloonexpandable branch graft stent system 120 is advanced over the guidewire260 as seen FIGS. 16B, 16C, and on into through the branch vessel whilecontinuing to follow the track provided by the guidewire 260 into aposition where the radiopaque images of the distal ring (hoop) stop 150and proximal (hoop) stop 152 straddle the opening 266 (marked byradiopaque markers or some other radiopaque visible marking scheme).

The branch graft stent system 120 extending into the branch vessel hasgraft material 138 and a stent 134 compressed on a balloon 128 (FIG.16C). Once in position (according to the ring stops 150, 152 discussedabove) the balloon 128 is inflated such that the bonded section 136 ofthe graft material sewn or bonded to the outside of the stent 134 comesinto engagement with the branch vessel wall 262 (FIGS. 15A, 16D). Theouter sheath 160 is retracted in a direction shown by the arrow 238 sothat as the open distal end of the sheath 160 moves closer to thecompressed location of the distal coiled nitinol hoop 156 and distalring (hoop) stop 150 (FIG. 15B). As the outer sheath 160 is furtherretracted, the distal coiled nitinol hoop 156 is allowed to expand toits unconstrained diameter configuration and is no longer axiallyconstrained by distal ring hoop stop 150 which remains fixed to thecatheter outer member (FIGS. 15C, 16E). Once the distal hoop is expandedit may be necessary to move the central members of the catheter assemblyforward (or distally) so that the proximal ring stop 152 is brought intoclose proximity to the location of the main vessel stent graft wall 250opening 266 having a hoop, grommet, or radiopaque marker 252 so thatwhen the proximal end of the stent graft system is deployed inengagement with or sealing with the main vessel stent graft wall, thesealing engagement can take place without kinking or a rolling of themain and branch graft materials as ring expansion and opening containingforces equalize at their point of contact. (Once repositioning of thecatheter to improve proximal alignment has occurred, the distal balloonmay be expanded, if necessary, to maintain position of the catheterduring the next step). The central inner and outer members 122, 144 canbe moved in a direction shown by arrow 240, 244 (FIGS. 15E, 16F.respectively) once the proximal ring stop 152 is in position (close to,but inside the main vessel branch opening marked by marker 252) theouter sheath 160 can be further retracted as shown by the arrow 238 torelease the proximal coiled nitinol hoop 158 from the outer sheath 182and the axial constraints of the proximal ring hoop stop 152. (FIGS.15F, 16G). Once the branch graft system has been deployed the deliverycatheter and guidewire can be removed to leave the branch graft material138 in a sealing engagement at a ring receiving pocket separationsection (sealing section) 153 with the main vessel stent graft wall 250.

The sequence for providing a branch graft stent system includes placinga guidewire through a main vessel stent graft side opening orfenestration, tracking a delivery catheter containing the stent graftbranch device into position, deploying the stent at the distal end ofthe device, retracting the sheath to initially release the distallylocated hoop or stent, repositioning the catheter to promote the releaseof the proximal or hoop sealing stent at the correct location,retracting the catheter to release the proximal hoop, and removing thedevice. An inflatable balloon may or may not be used to re expand thestent or sealing portion in a both balloon expandable and self expandingbranch stent graft catheter system. Balloon can also be used to expandstent graft opening 250 after branch vessel graft delivery. Note:Balloon can also be used to expand stent graft opening 250 after branchvessel graft delivery.

Referring now to FIGS. 17, 18, 19, and 20, a primary graft 270 isdisposed in a primary vessel and has a branch graft opening or port 272constructed of an insert molded (combination molded) silicone ring thatincludes enhanced radiopacity by use of known flexible radiopaquematerials. The branch graft assembly 271 can be constructed of a tubulargraft material with a proximal support spring (stent) 282 and a distalspring (stent) 284 which in an expanded configuration engages the wallsof the renal artery 280. The details of the connection feature betweenthe branch graft assembly 271 and the primary graft 270 includestructures, as discussed above, including a proximal ring structure 276and distal ring structure 278 (FIG. 18).

FIG. 19 is an alternate configuration of a branch graft assembly havingonly a distal spring (stent) 290 engaged with the renal artery 280. Theproximal ring structure 286 may include a (radiopaque) marker band orportion 287. Similarly, a distal ring structure 288 may include a markerband or portion 289.

FIG. 20 shows an alternate configuration of a branch graft assemblywhere the branch is constructed of flexible and/or reinforced materialhaving a threaded or ring like or accordion like elements or crimps tospan the aneurysmal sac and seal to the inner walls to the renal artery280. The branch graft assembly of FIG. 20 includes a proximal ringstructure 296 and a distal ring structure 298 constructed as describedin detail above for the balloon expandable and self expandingassemblies.

The description above is intended by way of example only and is notintended to limit the spirit and scope of the invention or itsequivalent as understood by persons skilled in the art.

1. A graft system, comprising a tubular branch graft having a proximalend, a distal end and a lumen extending along a tubular branch graftaxis longitudinally therethrough, said tubular branch graft comprising:a branch graft material; a first pocket material sewn to said branchgraft material at a first pocket proximal pocket seam and a first pocketdistal pocket seam to define a first circumferential graft pocket ofsaid branch graft; and a second pocket material sewn to said branchgraft material at a second pocket proximal pocket seam and a secondpocket distal pocket seam to define a second circumferential graftpocket of said branch graft; a first self expanding support ringcontained within said first circumferential graft pocket, said firstcircumferential graft pocket circumferentially encircling said branchgraft at said proximal end; and a second self expanding support ringcontained within said second circumferential graft pocket, said secondcircumferential graft pocket circumferentially encircling said branchgraft at said proximal end; wherein said second circumferential graftpocket is disposed approximately parallel to and a pocket sectionseparation length along said graft axis from said first circumferentialgraft pocket, wherein said second circumferential graft pocket islocated closer to said distal end of said branch graft than said firstcircumferential graft pocket; a tubular main graft having main graftmaterial with a side opening having a perimeter; wherein a pocketsection separation portion of said branch graft material engages saidperimeter of said side opening to form a seal between said main graftand said branch graft when said first self expanding support ringcontained within said first circumferential graft pocketcircumferentially encircling said branch graft at said proximal end isdisposed inside said side opening of said main graft and said secondself expanding support ring contained within said second circumferentialgraft pocket circumferentially encircling said branch graft at saidproximal end is disposed outside said side opening of said main graft.2. The graft system of claim 1, wherein at least one among said firstself expanding support ring and said second self expanding support ringare a nitinol hoop or of a similar material with shape memorycharacteristics.
 3. The graft system of claim 1, wherein at least oneamong said first self expanding support ring and said second selfexpanding support ring are a nitinol stent or of a similar material withshape memory characteristics.
 4. The graft system of claim 1, whereinsaid pocket section separation portion is made from said branch graftmaterial forming said branch graft.
 5. The graft system of claim 1wherein at least one among said branch graft and said main graft is atleast partially formed from materials selected from the group ofmaterials comprising woven polyester, expanded polytetrafluoroethylene,and Dacron.
 6. The graft system of claim 1 wherein said side opening isformed on a side of said main graft.
 7. The graft system of claim 1wherein said branch graft further comprises a branch graft anchoringcomponent for holding at least said distal end of said branch graft incontact with a branch anatomical conduit.
 8. The graft system of claim 1wherein said graft system further comprises a sheath constraining saidbranch graft that forms one side of a flexible seal when said sheath iswithdrawn to a first position to expose said first self expandingsupport ring and further forms a second side of said flexible seal whensaid sheath is withdrawn further to expose said second self expandingsupport ring.